The goal of this application is to investigate the unexpected role we have recently identified for anti-Mllerian hormone (AMH) in supporting the metastatic and drug resistance properties of aggressive lung cancer. Lung cancer kills approximately 160,000 people in the US annually, with a 5 year survival rate of ~16%. As a chaperone protein, heat shock protein 90 (HSP90) is essential to support the activity of many proteins involved in oncogenesis, and HSP90 overexpression in tumors correlates with worse outcomes. The clinically promising HSP90 inhibitor ganetespib is showing considerable promise in late stage clinical trials, including those for NSCLC, and has recently been granted Fast Track status for NSCLC. Our initial goal was to understand and further improve the activity of this and other HSP90 inhibitors. Following extensive screening of a targeted siRNA library, we identified AMH and its receptor AMHRII as significant regulators of resistance to ganetespib. AMH is a member of the transforming growth factor (TGF)-? ligand family, and AMHRII heterodimerizes with co-receptors also required by TGF-? and BMP, influencing common effector cascades. The role for TGF-? signaling in NSCLC proliferation, survival and metastasis is well established, but no prior study has ever identified a role for AMH and AMHRII in this context. Our preliminary data suggests a novel autocrine-signaling loop involving AMH and AMHIIR in multiple NSCLC cell lines, and also suggest a monoclonal antibody to AMHRII sensitizes cells to HSP90 inhibition. AMHRII stability was recently shown to be highly dependent on HSP90, while we have shown that there is significant expression of AMH and AMHRII in a subset of lung cancer cell lines as well as in many primary lung cancers. We hypothesize that previously undetected autocrine AMH signaling plays a critical role in supporting the TGF-? pathway in a subpopulation of lung cancers, that AMH/AMHRII inhibition may potentiate the efficacy of ganetespib and other therapies, and that AMH and AMHRII may be utilized as biomarkers for tumor aggressiveness. Our long-term goals are to better understand the role of AMH and AMHRII in therapeutic response to ganetespib and other agents, and use this information to improve the treatment of lung cancer patients. In this proposal, the first aim will use siRNA and overexpression experiments to probe the functional interactions of AMH with TGF-? signaling in lung cancer cells. The second aim will explore the in vitro and in vivo effects of inhibiting AMH and AMHRII for drug response, and use tissue microarrays of human lung cancer to gauge expression of AMH, AMHRII, HSP90 and related partners as predictors of tumor stage, grade, and prognosis.